The announcement by Danish pharmaceutical firm Lundbeck on Friday that it is restricting the distribution of pentobarbital represents a landmark decision. This is the first time that a major global pharmaceutical company has taken such direct action to tighten up its supply chain to ensure that its drugs are used to benefit the health of patients, not assist in state-sponsored execution. It follows months of pressure from human rights advocates. At the end of last year, US death row states found it difficult to get access to the previous drug, thiopental, for executions following an export ban from the UK.

Lethal injection is perceived as a more medical, and hence humane, method than hanging, stoning, shooting or electrocution. Yet the medicalisation of executions is an abomination of medical ethics, banned by all medical professional bodies, including the American Medical Association. Doctors' prime purpose is to help patients: "first do no harm" should be a doctor's credo, not assist in state-sponsored killing. Previously, the attention of human rights campaigners has been directed at the physicians and healthcare staff who have assisted in executions. Lundbeck's remarkable decision has, in effect, set an industry standard that no drug company should allow their products to be used for executions, even if without their authority.

Few doctors involved in executions have been prepared to go public. One who has, Dr Carlo Musso, was directly involved in Blakenship's execution. Dr Musso stated his opposition to the death penalty in a 2006 interview. Then, Dr Musso perceived his role as a palliative care physician on death row. "It just seems wrong for us to walk away, to abdicate our responsibility to the patients," he said at the time.

This year has seen a gear-change in the fight against lethal injection. The ban on imports into the US of the previous agent, thiopental, led to a strain on the death row supply chain. Dr Musso himself has recently been reported for allegedly illegally importing thiopental for executions. As a consequence of the thiopental shortage, US executioners have, for the first time, switched to using pentobarbital – a drug licensed for the treatment of the most refractory forms of epilepsy, not killing. Last month, I and over 60 other doctors published an open letter to pentobarbital's Danish manufacturer, Lundbeck, in the Lancet to "stop issuing platitudes" and tighten up their supply chain to prevent the abuse of pentobarbital for executions.

Lundbeck's CEO had stated that he "strongly opposes the use of pentobarbital for executions" and has written to all the death penalty states stipulating its opposition. When the states involved ignored Lundbeck's position and continued with botched executions, Lundbeck took today's action, which will "deny distribution of pentobarbital to prisons in US states currently carrying out the death penalty by lethal injection". There is, in fact, no legitimate use of this drug in a prison: if a patient is so ill that they need pentobarbital, they should be in a critical care unit with intensive monitoring, not languishing on death row. Finally, Lundbeck realised that the pharmaceutical industry, like doctors, should be about producing high-quality therapeutics to improve patient's health, not kill people.

Today, there is a real opportunity to see the end of the death penalty in the US – if other manufacturers follow suit. Put bluntly, if another drug company ends up supplying death row, I and the more than 100 healthcare workers who have petitioned Lundbeck to date will be after them. The only way to see the end of the death penalty, as Dr Musso and Lundbeck have previously stated as their wish, is not involve oneself – whether physician or pharma. What threatened to be a PR disaster for Lundbeck, the firm has, by its action, turned into a human rights victory.

• This footnote was appended on 4 July 2011. News of the 18th person executed using pentobarbital, Richard Bible on 30 June, was received after publication.